The optimal functioning of a receiver in a telecommunications system depends upon, among other things, the compatibility of its receiving bandwidth with the data rate and modulation type of the transmitter that is the source of the signal. In an analysis of communications links, an incorrect setting of the receiving bandwidth can lead to erroneous conclusions about transmitter requirements. For example, in a computer analysis of the communications link between a satellite transmitter and a ground station receiver, it may be important to determine how much transmitter power is needed to achieve a given bit error rate. If the bandwidth setting for the receiver is incorrect, the predicted power requirement may be too low, in which case the communications system may fail because of insufficient power. In contrast, if the predicted power requirement is too high, the satellite may be burdened with unnecessary weight resulting from a more powerful transmitter being used in the space craft.
For example, a new Earth Resource satellite, whose mission requires it to transmit a given number of pictures daily to ground-based receivers is to be built. This requires achieving a given data rate, which, in conjunction with the transmitter's modulation type, would determine the optimal bandwidth for the receiver.
In a computer analysis of this case, it is desirable to be able to modify and test various transmitter parameters in order to arrive at the most efficient and economical configuration. However, changes in these parameters--e.g., in the modulation type--require corresponding changes in the receiving bandwidth. If the latter changes are not made, the analysis will result in errors with potentially expensive consequences. If a satellite with insufficient transmitter power is launched, the error cannot be corrected and the satellite will be useless for its intended purpose.
In a communications link analysis without the present invention, it is necessary to adjust the receiver's bandwidth setting each time there is a change in the transmitter parameters affecting bandwidth ratio: Alternatively, one can set up a separate receiver for each different bandwidth setting that may be required. Both of these alternatives are time consuming and do not allow a wide range in transmitter parameters to be tested. More seriously, reliance on such measures entails a significant risk of error.
To overcome the shortcomings of the above approach, a method and apparatus are needed that will adjust the bandwidth setting of the receiver in a computer analysis of communications links automatically taking into account the changes in transmitter parameters affecting bandwidth ratio. Such a method and apparatus will provide the user with a bandwidth autoscaling option that can be used in lieu of setting the receiving bandwidth manually. The auto-scaling capability would take into account such transmitter parameters as data rate and modulation type, and set the receiving bandwidth to the correct frequency range, thereby allowing design of the optimal transmitter.